The present invention relates to a television system suitable for use in receiving a video signal containing a cinemascope image and, particularly, to such a television system capable of improving a resolution of a cinemascope image on a conventional television receiver screen by an effective utilization of upper and lower portions of the screen where there is no image displayed.
Responsive to recent demand for a high quality television system, various systems have been proposed. As an example of such proposals, Massachusetts Institute of Technology developed a single channel, high resolution television system. According to this system, a vertical dimension of an NTSC frame is reduced and signals providing an improvement of resolution are arranged in a space provided by the reduction of the vertical dimension of the frame. (cf. "Spectrum" No. 11, pp 20 to 25, Nov. 1988, Maruzen Co.)
As another example, a proposal for improving a vertical resolution of a television screen having an aspect ratio of 3:4 has been made in which resolution improving scan lines corresponding in number to required scan lines are formed in a television receiver to scan lines each disposed between adjacent scan lines of an image and carrying a signal thereon which corresponds to a difference between signals on the adjacent scan lines, so that the number of scan lines appears doubled.
The above mentioned single channel, high resolution system improves only the vertical resolution of the image, so that the degree of resolution improvement of image may be partial.
On the other hand, in the scan line doubling technique, it is very difficult, in a transmission side, to transmit all of the scan lines even when the additional scan lines are assigned to a portion or portions which are free from an image signal as in the case of cinemascope image transmission. Therefore, this technique could only effective in improving the vertical resolution if the above difficulty were overcome.